Drugs Flashcards
Contraindications for emetics
Brachycephalic airway disease, laryngeal paralysis, hiatal hernia, hypovolemic, ingestion of corrosive substance or already symptomatic from toxin
Mechanism of action of Hydrogen Peroxide
Direct gastric irritant, risk of ulceration and inflammation
When would H2O2 peroxide be a good choice for an emetic? Bad choice?
Good choice: Client financially restricted, can’t make it to vet - only for dogs
Bad choice: Cats! severe hemorrhagic gastroenteritis
Mechanism of action of apomorphine
Dopamine receptor agonist (CRTZ, central), also has anti-serotinergic effects that kick in afterwards and can lead to sedation/resp depression (rare)
When would Apomorphine be a good choice for an emetic? Bad choice?
Good: Hospitalized - since usually given IV (and IV admin leads to rapid induction of vomiting)
Bad: Not effective in cats!!!
Mechanism of action of dexmedetomidine?
Dexmedetomidine is an alpha 2 adrenergic agonist that acts directly on CRTZ … IM works better than IV
When is Dexmedetomidine indicated for emesis?
Cats! Since can’t give cats hydrogen peroxide and apomorphine isn’t that effective.
Mechanism of action of ropinirole?
Emetic, dopamine receptor agonist (like apomorphine), acts at CRTZ (central)
Clinical uses for ropinirole as an emetic?
Dogs! Ophthalmic drops –> easy administration, owner’s can give at home, good for repeat offenders (recently approved)
2 contraindications for antiemetics
1) If the animal has a gastrointestinal obstruction (masks signs of obstruction and could delay care –> perforation –> sepsis
2) Puppies <3 months (e.g. for parvo) can cause bone marrow hypoplasia
Mechanism of action of Maropitant?
NK1 receptor antagonist (central/peripheral), blocks action of substance P centrally, directly blocks NK1 receptor peripherally
Clinical uses/considerations: Maropitant?
Best choice for dogs and cats for anti-emesis, does cause pain on injection (cooling helps), efficacious against motion sickness!
Mechanism of Action of Odansetron
Odansetron is a serotonin antagonist that acts at the 5-HT3 receptor (centrally and peripherally)
Clinical use/considerations for Odansetron
2 choice antiemetic for dogs/cats… less effective than maropitant, more effective than Metoclopramide
Especially good for chemotherapy nausea
IV - fast acting - hospital use
Note - off label use (approved for humans, used in animals)
Mechanism of action of Metoclopramide as an anti-emetic
Metoclopramide is a dopamine antagonist (blocks 5HT3 receptors) - centrally
Clinical uses/considerations for Metoclopramide as an anti-emetic
Less effective in cats - thought to have fewer dopamine receptors
Less effective than Maropitant or Odansetron … won’t work well when there is a severe stimulus for vomiting (like acute pancreatitis)
Prokinetic effects so avoid if obstructed
Don’t use with phenothiazines since also causes extrapyramidal effects
Needs to be given in hospital
CRI may help effectiveness
Mechanism of action of Phenothiazines for antiemesis and 2 major side effects that limit use these days
Act at myriad central receptors (CRTZ and vomiting center)
May cause sedation and hypotension - rarely used
What is the #1 choice for prokinetic drug for dogs and cats? Is it for use in hospital or at home?
Metoclopramide, dopamine antagonism prevents vomiting but prokinetic mechanism poorly understood.
Needs to be used in hospital (IV/CRI) and also can’t be used with phenos.
Good choice if animal also nauseous because it has prokinetic effects
Whats the #2 choice of prokinetic drugs for dogs and cats? MOA? Is it for use in hospital or at home?
Cisapride! It’s a 5HT4 serotonin antagonist.
Needs to be compounded, otherwise would be #1 up there with metoclopramide ….
Can be useful for preventing reflux (but doesnt improve esophageal motility)….
Oral only, better for at home use (or tube feed in hospital if animal sick)
Which antibiotic can be used as a prokinetic by stimulating motilin receptors? Indications for use? Problems?
Erythromycin
Good for intestinal motility (contraction of smooth muscle)
Short term only
Animals can develop tolerance with long term use - tachyphylaxis
What should you address first before giving an appetite stimulant
Nausea! (otherwise animal will develop a learned food aversion … not good)
1st choice appetite stimulant in dogs that must be avoided in cats? MOA?
Capromorelin, ghrelin analog
1st choice appetite stimulant for cats (2nd choice for dogs?) MOA? Important considerations?
Mirtazapine, tetracyclic antidepressant
Dosing must be exact, so if you can’t get it to be perfect based on formulations, don’t use…. otherwise adverse CNS stimulation
2nd choice appetite stimulant in cats (that can’t be used in dogs)? MOA?
Cyproheptadine, H1 receptor antagonist and 5 HT 2 antagonist, avoid in dogs….
